In oil field operations, reciprocating pumps are often used for various purposes. Some reciprocating pumps, generally known as “service pumps,” are typically used for operations such as cementing, acidizing, or fracing a well. Typically, these service pumps run for relatively short periods of time, but they operate on a frequent basis. Often they are mounted to a truck or a skid for transport to various well sites. A pump might operate several times a week. In many applications, several pumps are connected in parallel to a single flow line.
Referring to FIG. 1, a reciprocating pump assembly or pump 11 includes a crankshaft housing or power frame housing 13 that comprises a majority of the outer surface of reciprocating pump 12. A plunger or plunger rod housing 15 attaches to an end of power frame housing 13 and extends to a set of cylinders 17. A portion of reciprocating pump 12 housed within power frame housing 13 is shown. Power frame housing 13 houses a crankshaft 25, which is typically mechanically connected to a motor (not shown). The motor rotates crankshaft 25 in order to drive reciprocating pump 12. In one embodiment, crankshaft 25 is cammed so that fluid is pumped from each cylinder 17 at alternating times. As is readily appreciable by those skilled in the art, alternating the cycles of pumping fluid from each of cylinders 17 helps minimize the primary, secondary, and tertiary (et al.) forces associated with reciprocating pump 12. In one embodiment, a large main gear or bull gear 24 is mechanically connected to each end of crankshaft 25. A small gear or pinion 26 is in mechanical engagement with each bull gear 24. A motor (not shown) couples to a splined end 29 of pinion shaft 27 (FIG. 2). The gear teeth on pinion 26 on each end are helical or inclined relative to the axis of pinion shaft 27. The inclination of the teeth on one pinion 26 is opposite that on the other. Bull gears 24 are rotated by the motor through the mechanical engagement of bull gears 24 and pinions 26.
As shown in FIGS. 1 through 3, reciprocating pump assembly 11 has a large gear or bull gear 24 one each side, and a smaller gear or pinion 26 in mechanical engagement with one another. Each bull gear 24 is mechanically connected to a crankshaft 25. Gear sections of pinion 26 are located at opposite ends of the pinion shaft 27, with a splined end 29 extending from one end of shaft 27. Shaft 27 passes through the power frame housing 13 of the reciprocating pump assembly 11.
Near each end of shaft 27, a pinion bearing assembly 31 comprising an inner race 33, an outer race 35, and spherical bearings 37 is shrunk-fit around a desired portion of pinion shaft 27. Although referred to as “spherical,” bearings 37 are generally cylindrical, but with outward curved sides between its ends. A bearing housing 39 fits around the outer race 35 of bearing assembly 31. Bearing housing 39 contains a lip 43 around its outer surface that acts to capture bearing assembly 31 once bearing housing 39 is securely fastened to power frame housing 13. Bearing housing 39 is bolted to a frame housing 40 by bolts 42. Frame housing 40 is welded to power frame housing 13. An outer housing surrounds gears 24, 26 and is filled with a lubricating fluid.
Assembly and installation of the pinion 26, and in particular, the bearing housing 39 to power frame 13 requires hammering of the bearing housings 39 into the power frame 13. While doing so, bearing housing 39 may become misaligned with bearings 37. The installation process is time consuming and inefficient. Thus, an improved design for facilitating engagement between the various components of reciprocating pump assemblies is needed.